The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its significance to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an admission that such art is widely known or forms part of common general knowledge in the field.
Pneumatic wheel sanders are well known. Typically, the tire of these sanders include a valve similar to those used in motor vehicle tires. The valve is either positioned axially on the wheel or is alternatively offset from the wheel axis. If positioned axially, the valve does not affect the balance of the tire. However, complicated wheel configurations not inherently suitable for mass production are often required with axially located valves. On the other hand, if the valve is offset, it tends to cause excessive wheel vibration when rotated at high speed, particularly where tires with diameters of greater than 4 inches are used.
Prior art pneumatic sanding wheels also often include a central hub having an internal female thread at one axial end thereof for engagement with a male thread on an external drive shaft. Accordingly, in order for the wheel to be connected to a drive shaft having a male thread of differing diameter to that of the female thread of the wheel, a thread adapter is required between the wheel and the drive shaft. The provision of the adapter increases the cantilevering effect of the wheel from the drive shaft and therefore exaggerates any wheel inertia and vibration effects.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.